Loans and Leases (Aging Of The Outstanding Loans and Leases By Class Excluding Loans Impaired At Acquisition Date) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	$ 22,833,827	$ 20,928,709
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	14,799,054	13,760,703
Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	669,215	649,157
Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	9,729,022	9,026,220
Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	473,433	351,291
Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	2,730,407	2,567,501
Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	894,801	826,270
Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	302,176	340,264
Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	8,034,773	7,168,006
Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	248,289	231,400
Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	3,523,786	2,889,124
Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	2,701,525	2,601,344
Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-PCI Loans	1,561,173	1,446,138
Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	144,872	129,252
Current	22,688,955	20,799,457
Non-PCI Loans	22,833,827	20,928,709
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,290	2,170
Current	667,925	646,987
Non-PCI Loans	669,215	649,157
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	21,153	24,694
Current	9,707,869	9,001,526
Non-PCI Loans	9,729,022	9,026,220
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	182	310
Current	473,251	350,981
Non-PCI Loans	473,433	351,291
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	9,470	11,071
Current	2,720,937	2,556,430
Non-PCI Loans	2,730,407	2,567,501
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	4,123	2,482
Current	890,678	823,788
Non-PCI Loans	894,801	826,270
Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	327	270
Current	301,849	339,994
Non-PCI Loans	302,176	340,264
Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	7,926,446	7,079,751
Non-PCI Loans	8,034,773	7,168,006
Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	8,641	2,294
Current	239,648	229,106
Non-PCI Loans	248,289	231,400
Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	57,851	50,079
Current	3,465,935	2,839,045
Non-PCI Loans	3,523,786	2,889,124
Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	27,135	24,402
Current	2,674,390	2,576,942
Non-PCI Loans	2,701,525	2,601,344
Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	14,700	11,480
Current	1,546,473	1,434,658
Non-PCI Loans	1,561,173	1,446,138
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	80,031	72,876
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	491	1,845
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	12,288	11,592
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	107	310
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	6,694	7,918
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	2,983	1,175
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	188	72
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	57,280	49,964
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	7,154	1,139
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	27,886	27,760
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	13,428	14,290
Financing Receivables, 30 to 59 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	8,812	6,775
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	19,050	18,472
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	442	39
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	2,375	2,773
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,510	2,102
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	167	444
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	6	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	14,550	13,114
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	108	598
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	8,064	7,039
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	3,485	2,698
Financing Receivables, 60 to 89 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	2,893	2,779
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	45,791	37,904
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	357	286
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	6,490	10,329
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	75	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,266	1,051
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	973	863
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Commercial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	133	198
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Noncommercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	36,497	25,177
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,379	557
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	21,901	15,280
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	10,222	7,414
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 2,995	$ 1,926